Nebulizer

ABSTRACT

A nebulizer comprises a head detachably coupled to a body. The head comprises nebulizing means, an air channel and a flow sensor. A nebulized liquid is released in an air channel that ends in a mouth piece through which a user inhales and exhales. The inhaling and exhaling causes a flow in the air channel which is detected with the flow sensor. The nebulizing means are controlled by control means included in the body.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a Continuation of U.S. patent applicationSer. No. 13/379,841, filed Dec. 21, 2011, which claims benefit under 35U.S.C. §371 of International Application No. PCT/IB2010/053299 filed onJul. 20, 2010, which claims the benefit of European Patent ApplicationNo. EP09166078.7 filed Jul. 22, 2009, the contents of which are hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a nebulizer comprising a head and a body, thehead being arranged for nebulizing a liquid and being detachably coupledto the body to facilitate cleaning of the head. The invention furtherrelates to a nebulizer system comprising the nebulizer and a personalcomputer which are coupled for data exchange. The invention furtherrelates to a method of detecting an inhaled or exhaled breath of aperson using the nebulizer and to a method of training a person in theuse of the nebulizer.

2. Description of the Related Art

Nebulizers are known in the art. See for examplehttp://ineb.respironics.com/ for a nebulizer of the applicant. Anebulizer works most efficient and causes the least environmentalpollution when it is breath activated. When working breath activated,aerosol is only delivered during inhalation and not during exhalation.An advanced implementation of breath activated aerosol delivery is knownas Adaptive Aerosol Delivery or AAD, see for examplehttp://ineb.respironics.com/AAD.asp.

After use the nebulizer any remaining medicine must be removed and thenebulizer must be cleaned well before it can be used again. For examplepatients suffering from Cystic Fibrosis are susceptible to infectionsand any contamination of the nebulizer must be prevented. This requiresthat all parts that have been in contact with a medication liquid and/orthe inhaled or exhaled air must be desinfectable using for example steamcleaning or ethanol immersion.

It is an object of the invention to provide a nebulizer that facilitatesan easy and good cleaning.

SUMMARY OF THE INVENTION

The object is achieved with the nebulizer according to claim 1. Thenebulizer comprises a detachable head to enable an easy disinfecting ofthe head. The body does not suffer from a frequent cleaning with forexample steam cleaning which enhances the lifetime of the body. Byhaving the sensing means included in the head instead of for examplehaving a pressure sensor included in the body and coupled with aseparate channel to the air channel the inhaled and exhaled breath arenot in contact with the body. Thus only the nebulizing means and the airchannel included in the head of the nebulizer are in contact with theliquid, nebulized liquid or the inhaled and exhaled breath of the user.This reduces possible sources of contamination. The controlling meansincluded in the body controls the nebulizing of the liquid.

The head comprises the medication chamber which may be filled with aliquid, for example a dissolved medication. The vibration sourceincluded in the head transfers vibrations to the liquid such that theliquid is ejected through the holes of the mesh to form small dropletsin the air channel.

For cleaning, the head may be opened to obtain access to the parts(e.g., the nebulizing means) that may contact the inhaled or exhaledbreath, the liquid or the nebulized liquid such as the air channel, themedication chamber, the vibration source and the mesh.

The head and the body may be parts that are coupled using a cable. Thecable provides the energy transfer or control signals from the body tothe head as well as the signal transfer from the sensing means (e.g.,flow sensor or pressure sensor) positioned in the head to a controllingmeans included in the body. The signal from the sensing means may be ananalog or a digital signal. In this embodiment the head is detachablefrom the body by disconnecting of the cable from for example only thehead. This may for example be realized using a plug—socket couplingbetween the cable and the head. In use the body with the controllingmeans is for example placed on the table and the cable is connected tothe head which is hold by the user. In this embodiment the energy source(e.g., battery) is included in the body resulting in a relativelightweight head.

In another embodiment of the nebulizer the head and the body parts havea shape and/or mechanical interface to enable a direct connection of thehead to the body to form one unit that is hold by the user. When thehead is clamped to the body also an electrical coupling between the headand the body is established to enable energy transfer from the body tothe head and signal transfer from the head to the body.

In a further embodiment the nebulizing of the liquid is dependent on thesignal received from the sensing means.

In a further embodiment the sensing means comprises a pressure sensor.The pressure in the air channel drops during an inhalation and increasesduring an exhalation. The signal of the pressure sensor can therefore beused to distinguish between inhaling and exhaling.

In a further embodiment the sensing means comprises a flow sensor. Theflow sensor detects the flow in the air channel. With the signal of theflow sensor inhaling and exhaling can be distinguished.

In yet a further embodiment of the nebulizer the flow sensor is athermal flow sensor device arranged to sense a flow in the air channelwhich is caused by the inhaled and exhaled breath of the user. The flowcauses a temperature gradient across the surface of the thermal elementthat is included in the flow sensor device and based on a temperaturemeasurement the flow in the air channel is sensed. For example thethermal element may comprise a heating element with two temperaturesensing element at opposing sides of the heating element, and allpositioned in a same plane along which a flow caused by the inhaled andexhaled breath passes.

The thermal flow sensor device may comprise an electrically driventhermal element on its front side which faces the interior of the airchannel. The inhaled and exhaled breath causes a flow through the airchannel that passes the thermal element and causes a temperaturegradient which is detected by the thermal flow sensor device andconverted to the signal that is used by the nebulizing controlling meanswhich are included in the body.

In yet a further embodiment the thermal flow sensor device or thepressure sensor is built in a wall of the air channel. Because ofhygiene the thermal flow sensor device or the pressure sensor may beintegrated in the wall thereby obtaining a smooth inner surface of theair channel that may be cleaned easily. For example the wall may have arecess with a shape that matches with the dimensions of the thermal flowsensor device or pressure sensor.

The pressure sensor may comprise an integrated circuit die. In anembodiment the pressure sensor is a MEMS pressure sensor capable ofproviding a signal that is dependent on the absolute pressure. MEMS orMicro-Electro-Mechanical Systems refers to the integration of mechanicalelements, sensors, actuators, and electronics on a common siliconsubstrate through integrated circuit (IC) process sequences (e.g., CMOS,Bipolar or BICMOS processes). The MEMS pressure sensor comprises acapacitor of which a distance between the plates is dependent on thepressure in the air channel. For example a low pressure causes thedistance to increase and the capacitance to decrease. Likewise a highpressure in the channel causes the distance to decrease and thecapacitance to increase.

The thermal flow sensor device may comprise an integrated circuit die onwhich the thermal element is integrated.

In an embodiment of the integrated circuit the die has a component sideon which the thermal element is located and a back side on which thebondpads for connecting the thermal element are located. When thethermal flow sensor device is positioned in the recess in the wall thecomponent side of the die faces the interior of the air channel. Byhaving the bondpads accessible from the backside of the integratedcircuit die the space needed for the bondpad and any connection to it donot influence the flow of the inhaled and/or exhaled breath along thethermal element. This improves the sensitivity and performance of thethermal flow sensor device.

In a further embodiment of the integrated circuit the heating element isrealized as a polysilicon resistor and the temperature sensing elementsare realized as a string of polysilicon-metal junctions. Themanufacturing of this heating and temperature sensing element requiresonly a limited number of processing steps while the feature size of theused lithography may be relatively large.

In yet a further embodiment said die is glued with its component side ona thin glass plate. The thickness of the plate is chosen to have a lowthermal resistance and provides the die mechanical stability. Bondpadsat the backside of the die are obtained using an etching processing stepof selected positions of the substrate.

With a heating element flanked by two thermal sensing elements, one ateither side, a temperature difference caused by a flow can be measured.The sign (positive or negative) of the measured temperature differencecorresponds with the flow. Hence with this simple thermal element aninhaled breath can be distinguished from an exhaled breath, which may beused to obtain AAD.

In yet a further embodiment of the nebulizer the mesh is detachablycoupled to the medication chamber. This enables a replacement of themesh as well as a simple emptying of the medication chamber after use orduring cleaning of the head. After frequent use the mesh performance maydeteriorate, for example because residues obstruct some percentage ofthe many small holes of the mesh.

To prevent spillage when only a small amount of medication liquid needsto be taken by the user the medication chamber may be formed such thatits volume is small. This may be realized by placing the mesh close tothe vibration source such that they are separated from each other by asmall gap. The gap should still be large enough to enable the vibrationsource to cause in use a standing wave in the liquid filled medicationchamber. For efficient operation of the nebulizer the dimension of thegap, the distance between the mesh and the vibration source, should beapproximately n*Lambda/2 [m], wherein Lambda=v/f, v being the speed of awave [m/s] in the medication liquid caused by the vibration at afrequency f [Hz] and n being an integer larger than 0. For efficientoperation and a medication chamber with a small volume n is chosen inthe range of 1 to 3.

When the head is coupled to the body an electrical coupling between themis established to enable energy transfer from the body to the head andsignal transfer from the head to the body. This electrical coupling maybe realized with metal elements that contact each other when the head iscoupled to the body. However a frequent cleaning of the head may resultin a decreased contact quality for example because of oxidation of themetal. Or steam may enter the head through minuscule channels betweenthe metal and the plastic housing of the head. In a further embodimentof the nebulizer the electrical coupling between the body and the headis realized with a magnetic field coupling between the head and thebody.

The head may comprise a receiver coil electrically coupled to thevibration source and the body may comprise a transmitter coil coupled toan AC current or AC voltage source, the receiver and transmitter coilbeing aligned such that when the head is attached to the body thetransmitter and receiver coil are magnetically coupled. An AC current inthe transmitter coil causes a magnetic field which on its turn causes acurrent in the receiver coil, thereby providing a wireless powering ofthe head.

To optimize the magnetic field coupling between the head and the body asplit transformer may be used. The split transformer comprises a corewhich is split in at least two parts. The first part is included in thehead; the second part is included in the body. Each of these two coreparts has its corresponding winding. When the head is attached to thebody the two core parts align and the split transformer operates as atransformer having a core with two air splits.

As an example each part of the split core may have a U shape. When thehead is attached to the body the ends of the legs of the two U shapedcores face each other and have an air gap between them. The receiver andtransmitter coils each are wound around their respective U shaped core.Other shaped cores like an E shape may also be used to have for exampletwo pairs windings on the split transformer. A first pair comprises aprimary winding at a first E core on the transmitter side in the bodyand a secondary winding at a second E core at the receiver side in thehead and may be used to transfer a drive signal and energy for thevibration source. A second pair comprising a further primary winding atthe first E core and a further secondary winding on the second E coremay be used to transfer energy for a flow sensor supply which isincluded in the head to power the flow sensor circuitry.

In the head the receiver coil may be coupled to the vibration source,which for example is a piezo electric element. The number of windings ofthe receiver and transmitter coil may be different to obtain apredetermined driving voltage for the piezo electric element. In thisembodiment the frequency of the AC current corresponds to the vibrationfrequency of the piezo.

In a further embodiment the frequency of the AC current is chosen above1 MHz to obtain small dimensions for the split transformer and a narrowgap of approximately Lambda/2 [m] between the mesh and the vibrationsource to obtain medication chamber with a small volume.

The signal from the flow sensor may be transferred from the head to thebody with a magnetic field and/or optical coupling between the head andthe body.

In yet a further embodiment the nebulizer comprises communication meansto provide a data exchange with a personal computer (PC), the PC and thenebulizer together forming the nebulizing system. The coupling betweenthe nebulizer and the personal computer may be wireless or wired, forexample with a USB coupling. Flow data dependent on the signal from thesensing means may be transmitted by the communication means from thenebulizer to the PC. The flow data may be used to train the person inthe use of the nebulizer. For example the nebulizer or the PC may givean instruction to the person to inhale and/or exhale with his mouthcoupled to the mouthpiece of the nebulizer such that his inhaled and/orexhaled breath causes a flow through the air channel. A programmedalgorithm running on the PC interprets the received flow data and givesvisual and/or audible feedback to the person such that the person istrained before the person starts using the nebulizer with medicineliquid.

In a further embodiment the visual and/or audible feedback is given bythe nebulizer itself, the algorithm interpreting the signal from theflow sensor being implemented on the processor which is included in thenebulizers' body.

The invention further provides a method of detecting the inhaled orexhaled breath of the person using a nebulizer. The method includes thestep of measuring the flow in the air channel with sensing means in thedetachable head, the flow being caused by the inhaling or exhaling ofthe person. While breathing the air channel is coupled with themouthpiece to the mouth of the person causing the flow through the airchannel.

Any additional features can be added, some are described in more detailbelow. Any of the additional features can be combined together andcombined with any of the aspects, as would be apparent to those skilledin the art. Other advantages will be apparent to those skilled in theart, especially over other prior art. Numerous variations andmodifications can be made without departing from the claims of thepresent invention. Therefore, it should be clearly understood that theform of the present invention is illustrative only and is not intendedto limit the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

How the present invention may be put into effect will now be describedby way of example with reference to the appended drawings, in which:

FIG. 1 shows an embodiment of a nebulizer according to the invention;

FIG. 2 shows an embodiment of an air channel;

FIG. 3 shows an embodiment of an integrated circuit;

FIG. 4 shows an air channel with a thermal flow sensor; and

FIG. 5 shows a further embodiment of a nebulizer.

The drawings described are only schematic and are non-limiting. In thedrawings, the size of some of the elements may be exaggerated and notdrawn on scale for illustrative purposes.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims.

FIG. 1 shows a nebulizer 10 comprising a head 20 and a body 30 whereinthe head is detachable from the body to facilitate for example steamcleaning of the head after use. The body comprising controlling means60, 62 may be rinsed to clean it. Steam cleaning is not necessary as thebody has no direct contact with a medication liquid or inhaled 5 orexhaled 7 breath. This is advantageous for the expected lifetime of thebody as the steam can have a detrimental effect on electronic circuitssuch as the controlling means that are included in the body. The headcomprises a medication chamber 40, a vibration source 44 such as a piezoelectric element, a mesh 42 and an air channel 50. The vibration sourceis activated by the driving circuit 60 to cause a standing wave in theliquid. The liquid may for example comprise a medication dissolved inwater and is also referred to as medication liquid. The standing wavebetween the vibration source and the mesh causes the ejection ofdroplets in the air channel. The air channel ends at one side in amouthpiece 70 and at the other side in an ambient port 51 which is inopen contact with ambient air. A user puts the mouthpiece 70 against hismouth and inhales 5 and exhales 7 causing a flow through the airchannel. The inhaling and exhaling is detected by the sensing means 52and an output of the sensing is coupled to the controlling means 60, 62.A signal 54 indicative of the inhaling and exhaling is used by thecontrolling means to synchronize the driving circuit 60 with thebreathing such that for example during exhaling the nebulizing of themedication liquid is interrupted. To allow cleaning the head can beopened, for example along line 43, to allow access to the interior ofthe air channel as well as to the mesh 42. The mesh is detachable fromthe medication chamber such that also the interior of the medicationchamber may be cleaned. A further advantage of a detachably coupled meshis that it can be replaced when its performance has worsened for examplebecause a predetermined percentage of the plurality of holes in the meshhas become obstructed.

When the head is coupled to the body an electrical connection betweenthe piezo driving circuit 60 and the vibration source 44 and between theflow sensor 52 and a processor 62 is obtained. The processor determinesthe driving frequency and duty cycle of a driving signal 45 which isprovided by the driving circuit 60 to the vibration source 44. Theelectrical coupling may be realized with a “plug-socket” type ofconnection. For durability and reliability it may be advantageous tohave a magnetic field coupling which is discussed later. The processor62 and the sensing means 52 may further have an optical coupling whichdoes not suffer from a possible interference caused by the magneticfield.

In FIG. 1 the nebulizing means may comprise a cylindrical shapedmedication chamber 40 having a detachably coupled mesh at one side and apiezo electric element glued to it at the other side. The volume of themedication chamber is preferably small to prevent that a relative largeamount of left medicine needs to be removed when cleaning the head. Thevolume can be minimized by reducing the distance or gap between the meshand the piezo electric element. However to obtain a standing wavebetween the piezo electric element and the mesh the distance should notbe smaller than approximately /2 [m], wherein is the wavelength. Thewavelength is dependent on the frequency of the vibration and thepropagation speed in the medicine. For efficient operation and amedication chamber with a small volume the distance between the mesh andthe piezo electric element is approximately /2 [m], [m] or 3 /2 [m]. Ina further embodiment of the nebulizing means the mesh 42 has a concaveshape to obtain an improved dispersion of the cloud of droplets in theair channel.

In the invention the flow caused by an inhaling or exhaling user isdetected by sensing means 52 which are included in the head 20 of thenebulizer. In a further embodiment the sensing means 52 are positionedto detect the flow in a portion of the air channel 50 between themedication chamber 40 and the ambient port 51 which has a smaller crosssection than a further portion of the air channel between the medicationchamber and the mouthpiece 70. By measuring the flow in the narrowerportion of the air channel the signal 54 from the sensing means providesa better representation of the actual flow in the air channel. Furtherthe value of the flow will be higher in the narrower portion therebyenhancing the sensitivity of the flow measurement.

The sensing means 52 may for example comprise a pressure sensor thatmeasures the pressure in the air channel 50. The pressure changes duringinhaling 5 or exhaling 7 of the user and therefore the pressure sensorenables the detection of the flow in the air channel.

In a further embodiment the sensing means may comprise a flow sensor.The flow sensor may for example comprise a valve that moves as a resultof the flow in the air channel. The movement of the valve may be used todistinguish between an inhaling and exhaling breath.

In a further embodiment the flow sensor comprises a thermal element andsenses the flow caused by the inhaled and exhaled breath based on atemperature measurement. Such a flow sensor is referred to as a thermalflow sensor device and has the advantage of not comprising any movingparts.

FIG. 1 further shows a nebulizing system comprising the nebulizer 10 anda personal computer (PC) 92. The nebulizer comprises communication means90 which enable a data exchange with the personal computer 92. In anembodiment of the system the user may couple the nebulizer with a USBcable 91 to his PC. The coupling may however also be wireless. A programon the PC may be used to train the person in the use of the nebulizer.For example the user may need to be trained in inhaling and exhalinghaving the nebulizer pressed against his mouth. In the training methodthe person is asked to inhale and exhale through air channel 50 of thenebulizer. The instruction for inhaling 5 and/or exhaling 7 may be shownon the screen of the PC. The sensing means 52 measure the flow caused bythe inhaling and exhaling of the person and data corresponding to themeasured flow is transmitted with the communication means 90 to the PC.In response to the received data feedback is given to the person. Thisfeedback may comprise further instructions such as for example tobreathe slower or deeper.

In a further embodiment the training method is implemented in theprocessor 62 of the nebulizer 10. The instructions to the person may begiven audible. Feedback may also be given audible, for example in termsof a sound indicating a pass when the inhaling and exhaling compliedwith predetermined criteria or a fail when during the training thebreathing did not comply with the predetermined criteria. In a furtherembodiment feedback is given visually for example on a LCD screen on thenebulizer body 30. The LCD screen may display for example furtherinstructions to breathe slower or deeper.

FIG. 2 shows a portion of the air channel 50. The inhaled 5 and exhaled7 breath cause a flow through the air channel which is detected with athermal flow sensor device 53. The thermal flow sensor device may forexample be positioned in a recess in the wall 58. After use the airchannel may be cleaned by opening the head as discussed earlier. Toprevent any residue the surface of the flow sensor device preferablymatches with the wall 58 surrounding it to obtain a smooth interior inthe air channel. The thermal element on the flow sensor device maycomprise a thermal heating element 56 a and two thermal sensor elements56 b surrounding it. In case there is no flow the two thermal sensorelements 56 b will both measure approximately the same temperature. Incase the left thermal sensor element measures a higher temperature thanthe right thermal sensor element the flow must be from right to left asthe flow transports the heat produced by the thermal heating element 56a causing a small rise in temperature of the left thermal sensingelement. Hence the detected flow was caused by an inhaling breath 5 ofthe user. Likewise the exhaling is detected by the thermal flow sensordevice.

In a further embodiment the flow sensor detects not only the directionof the flow in the air channel but also its rate. When a detected rateis above or below a predetermined threshold the controlling means maygive a warning to the user. In a further embodiment the nebulizer may beput in a training mode in which no atomization of the medicine takesplace and the user is instructed to inhale and exhale whereby thecontrolling means give a warning when the inhaling or exhaling iscausing a too large or too small flow for the nebulizer to workeffectively.

FIG. 3 shows a cross section of a portion of a processed integratedcircuit 130 that is part of the thermal flow sensor device 53. Facingupwards is the component side comprising a polysilicon (PS) resistor 300that is connected with a metal track 600. On top of the polysiliconresistor other layers may be formed such as a further metal layer 750which can be used to tune thermal conductivity. The metal track 600contacts the substrate 200 through a contact hole (CO) and after theback side etching of the substrate the backside (the side facingdownward) of the metal track is accessible and forms a bonding area orbondpad at the backside of the die. With the shown bonding 160 at thebondpad a connection with one of the two terminals of the PS resistor isrealized.

Before the etching of the substrate takes place the die is connected viaa glue layer 1000 to an electrical insulating substrate 900 such asglass. The thin layer (typically 400 micrometer) of glass provides agood thermal conductivity to the PS resistor. Further the glass layerprovides mechanical stability to the die to enable the etching throughthe substrate to the metal track.

The integrated circuit 130 further comprises thermal sensing elementssurrounding the heating element. A temperature difference between anytwo thermal sensing elements may be used to determine the flow directionin the air channel. The thermal sensing element may for example comprisea PN junction of which the forward voltage is dependent on temperature.In a further embodiment the thermal sensing element comprises a stringof thermocouples, each thermocouple comprising a polysilicon-metaljunction. This provides the advantage that no additional layers andprocessing is required to obtain the thermal sensing element as it ismade in the same process steps as the polysilicon resistor 300 and themetal track 600 and can be connected from the backside in the same wayas the PS resistor as discussed earlier.

In a further embodiment the thermal flow sensor device 52 in the airchannel 50 is calibrated using a predetermined flow with a knowndirection and rate. The detected temperature differences sensed by thethermal sensing elements are stored in a look up table. The look uptable may for example be stored in a memory comprised in the controllingmeans 60, 62. In use the temperature differences sensed by the thermalflow sensor device 53 are compared with stored values from the look uptable to determine the flow rate in the air channel.

The above discussed calibration method is also applicable for othersensing means such as a pressure sensor.

FIG. 4 shows a further cross section of a portion of a processedintegrated circuit 130 with a different implementation of the back sidecontacting. As in FIG. 3 the thermal heating element is realized with aPS resistor 300 that is connected to a metal track 600. The substrate200 in this implementation is however highly doped and therefore lowresistive. As discussed earlier the wafer (containing a plurality of thedies) is bonded (using glue 1000) to a glass layer 900. The backside ofthe wafer obtains a metal layer 210 on the substrate and is subsequentlyetched resulting in “electrically isolated pillars” 240 to remain. Shownis a pillar 240 that connects via the metal track 600 to a terminal ofthe PS resistor 300. The metal on the pillars forms bondpads and can becontacted with wire bonding or can be connected to pads on a printedcircuit board (PCB) 290 using stud bumps. An adhesive 330 is appliedbetween the PCB and the integrated circuit die 130 to preventpenetration of dirt or vapor. The thermal flow sensor device comprisesthe assembly of the integrated circuit 130 die and the PCB 290. Theassembly is mounted in a window in the wall 58 of the air channel andsealed to prevent leakage. The glass layer 900 faces the interior of theair channel. In a further embodiment the wall 58 has a locally thinnedpart in which the assembly is fitted such that the thinned partseparates the integrated circuit die from the interior of the airchannel. The thinned part provides an improved barrier to reduce a riskof leakage or contamination.

FIG. 5 shows a further embodiment of the nebulizer in which only thoseparts relevant for the discussion are shown. In this embodiment thedriver circuit 60 activates the vibration source 44 using a magneticfield coupling between the body 30 and the head 20. This provides theadvantage that no electrical contacts are accessible at the exterior ofthe head and the body. Electrical contacts at the exterior may damagedue to frequent decoupling of the head and the body or by frequent steamcleaning of the head. The magnetic field coupling comprises two U shapedcores 70, 71 of which the legs are aligned when the head is detachablycoupled to the body. When aligned the two U shaped cores make up a splittransformer having a primary winding 72 coupled to the driving circuit60 and a secondary winding 73 coupled to the vibration source 44, whichfor example is a piezo electric element. The winding ratio of thesecondary and primary winding can be used to obtain a predetermineddriving voltage for the piezo electric element. The frequency of acurrent provided by the driving circuit 60 and passing through theprimary winding 72 determines the vibration frequency and hence can beused to control the nebulizing of the liquid in the medication chamber.To obtain small dimensions for the split transformer the driving circuitshould provide a relative high frequent (e.g., above 1 MHz) AC drivecurrent through the primary winding 72. Having the secondary winding 73driving the piezo electric element 44 said relative high frequency mayfurther be used to provide the additional advantage of a relative narrowminimal gap of /2 [m], [m] or 3 /2 [m] between the piezo electricelement 44 and the mesh 42 resulting in the medication chamber having arelative small volume.

In a further embodiment the sensing means included in the nebulizers'head 20 is implemented as a thermal flow sensor device 52 or MEMSpressure sensor mounted in a recess of the air channel. The supply forthe sensing means is also obtained with a magnetic field couplingbetween the head and the body. The split transformer comprises anadditional secondary winding for powering the sensing means.

In a further embodiment the split transformer comprises two E shapedcores. The split transformer may have an additional primary windingcoupled with a magnetic field coupling to the additional secondarywinding. The additional primary and secondary windings for providingenergy to the sensing means are each made across the center leg of itscorresponding E shaped core whereas the primary and secondary windingfor the piezo drive are arranged on the outer legs of the E shaped core.This arrangement provides a separation between the primary winding andthe additional primary winding, and between the secondary and additionalsecondary winding resulting in a reduced interference.

Where the term “comprising” is used in the present description andclaims, it does not exclude other elements or steps. Where an indefiniteor definite article is used when referring to a singular noun e.g., “a”or “an”, “the”, this includes a plural of that noun unless somethingelse is specifically stated.

The term “comprising”, used in the claims, should not be interpreted asbeing restricted to the means listed thereafter; it does not excludeother elements or steps. Thus, the scope of the expression “a devicecomprising means A and B” should not be limited to devices consistingonly of components A and B. It means that with respect to the presentinvention, the only relevant components of the device are A and B.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order. It is to be understood that the terms so used areinterchangeable under appropriate circumstances and that the embodimentsof the invention described herein are capable of operation in othersequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. It is to be understoodthat the terms so used are interchangeable under appropriatecircumstances and that the embodiments of the invention described hereinare capable of operation in other orientations than described orillustrated herein.

What is claimed is:
 1. A nebulizer assembly comprising: a headcomprising: a nebulizer, an air channel in which the nebulized liquid isreleased, the air channel being arranged to guide a flow caused by aninhaled and exhaled breath of a user, the nebulizer comprising: amedication chamber for holding the liquid, a vibration source arrangedto transfer vibrations to the liquid, and a mesh, and wherein the airchannel is arranged to guide the flow along the mesh, and a sensorarranged to detect the flow, wherein all components of the nebulizerassembly that are in contact with the liquid and inhaled and exhaledbreath of the user are located in the head; and a body detachablycoupled to the head, the body comprising a controller adapted to controlthe nebulizing means, the controller including driving circuitry forcontrolling the vibration source.
 2. The nebulizer assembly according toclaim 1, wherein the controller is arranged to energize the vibrationsource based on a signal received from the sensor.
 3. The nebulizerassembly according to claim 2, wherein the signal corresponds only witha direction of the flow in the air channel.
 4. The nebulizer assemblyaccording to claim 1, wherein the sensor comprises: a pressure sensorarranged to sense the flow based on a pressure measurement, or a thermalflow sensor device arranged to sense the flow based on a temperaturemeasurement.
 5. The nebulizer assembly according to claim 4, wherein thethermal flow sensor device comprises an electrically driven thermalelement disposed on a front side of the thermal flow sensor device, thefront side facing the interior of the air channel.
 6. The nebulizerassembly according to claim 5, wherein the thermal flow sensor devicecomprises an integrated circuit die that includes an electrically driventhermal element disposed on the front side and one or more bondpads at abackside of the thermal flow sensor device opposite the front side, theone or more bondpads being electrically coupled to the thermal element.7. The nebulizer assembly according to claim 5, wherein the thermalelement comprises a heating element and at least two temperature sensingelements.
 8. The nebulizer assembly according to claim 5, wherein theair channel comprises a wall having a recess defined therein in whichthe thermal flow sensor device is mounted with the electrically driventhermal element facing the air channel.
 9. The nebulizer assemblyaccording to claim 5, wherein the mesh is detachably coupled to themedication chamber.
 10. The nebulizer assembly according to claim 1,wherein the medication chamber is formed such that the mesh is separatedfrom the vibration source by a gap, the vibration source being arrangedto vibrate at a frequency f, the mesh being separated from the vibrationsource by the gap forming a distance between the mesh and the vibrationsource of substantially Lambda/2, wherein Lambda=v/f, v being the speedof a wave in the liquid caused by the vibration at frequency f.
 11. Thenebulizer assembly according to claim 1, further comprising anelectrical energy source arranged to transfer energy from the body tothe head to energize the vibration source, the flow sensor, or bothusing a magnetic field coupling between the head and the body.
 12. Thenebulizer assembly according to claim 1, wherein the signal from thesensor is transferred from the head to the body using a magnetic field,an optical coupling, or both.
 13. A method of detecting an inhaled orexhaled breath of a person using a nebulizer, the method comprising thestep of: measuring with a sensor a flow in an air channel, the flowbeing caused by the inhaled or exhaled breath of a user, the air channelbeing arranged to guide the flow, the sensor including a head comprisingnebulizing element arranged to nebulize a liquid and release thenebulized liquid in the air channel, the nebulizing element comprising amedication chamber for holding the liquid, a vibration source arrangedto transfer vibrations to the liquid, and a mesh, wherein the airchannel is arranged to guide the flow along the mesh, wherein allcomponents of the nebulizer that are in contact with the liquid andinhaled and exhaled breath of the user are located in the head of thenebulizer, the nebulizer further comprising a body detachably coupled tothe head, the body comprising a controller arranged to control thenebulizing element, the controller including a driving circuit adaptedto control the vibration source.